EMC testing to the appropriate standard is required for imports into many countries. The EMC Directive only requires manufacturers to make a Declaration of Conformity listing the test standards they have “applied” when using the standards route to conformity. Customs officers may ask to see evidence that ‘due diligence’ has been achieved in the conformity of a given product at any time (most usually after a complaint by a competitor).
While full compliance EMC testing is not a burden for manufacturers of products made in large volumes, it can be disproportionately expensive for manufacturers of low cost custom engineered or small-batch products. So there is a need for pre-compliance testing to discover whether there are any major concerns before a mass produced item goes for full compliance testing. Such EMC pre-compliance testing has the advantage that tests can be stopped at any time, the equipment under test can also be modified and the test can restarted; whereas full EMC compliance testing is more expensive per day and allows no disruption in the test, or involvement by product designer. If EMC pre-compliance testing is good enough to pass the ‘due diligence’ requirement of the enforcers, it can be all that is needed for legal sales in the EU, which is good news for UK manufacturers of low-cost custom or small-batch equipment